Steampunk fan Chris Howard has posted a short tutorial on turning vintage city maps into maps of fictional places for use in gaming or as costume accessories. His method assumes you have some artistic talent, but you could do something similar with clip art.

Obviously, you don’t have to go steampunk. You could create maps of Dracula’s London or Poe’s Baltimore, or just use a map as a jumping-off point for a realm of your own devising. In addition game aids and props, they’d be lovely framed or used as part of an art project (books covered in old maps are especially striking).